Performance Of Asphalt Mixtures Research Articles

Predictive modeling of low-temperature performance of SMA-13 cold-patching asphalt mixtures based on fractal theory

In order to study the relationship between the low-temperature performance of cold-patching asphalt mixtures and the fractal of gradation, 13 groups of SMA-13 gradations were designed, and then the low-temperature performance test of cold-patching asphalt mixtures was carried out. The overall fractal dimension D, coarse aggregate fractal dimension Dc, fine aggregate fractal dimension Df were obtained by using fractal theory, and according to the correlation analysis of low-temperature performance and fractal dimension, the low-temperature performance prediction model of cold-patching asphalt mixtures based on fractal dimension was established.

Predictive Modeling of High Temperature Performance of SMA-13 Cold Patch Asphalt Mixture Based on Fractal Theory

In order to study the relationship between the high temperature performance of cold-patched asphalt mixtures and gradation fractal, 13 groups of SMA-13 asphalt mixtures were designed, and high temperature rutting test was carried out to study the high temperature performance of cold-patched asphalt mixtures, and the fractal theory was applied to get the overall fractal dimension D, coarse aggregate fractal dimension Dc, fine aggregate fractal dimension Df, and the predictive model of high temperature performance for cold-patched asphalt mixtures was set up according to the correlation analysis of the high temperature performance and fractal dimension. The high-temperature performance prediction model of cold-patched asphalt mixtures was established based on the correlation analysis between high-temperature performance and fractal dimension. This can reduce the test workload, improve work efficiency, and provide reference for engineering design.

Evaluation of cooling effect and road performance of warm mixed high viscosity porous asphalt mixture.

In order to study the effect of different warm mixing agents on the cooling and road performance of porous mixture bonded with High Viscosity Asphalt (HVA), the Superpave Gyratory Compactor (SGC) was proposed to conduct variable temperature compaction test on the warm mixed porous asphalt mixture. The relationship between the compaction difficulty coefficient and the temperature of the mixture was obtained by regression, and the mixing and compacting temperature and cooling effect of the warm mixed porous asphalt mixture were determined. Then, the influence of Evotherm M1 and EC120 warm mix agents on the performance of porous asphalt mixture was compared by rutting tests, beam bending tests, immersion Marshall tests, freeze-thaw splitting tests, and penetration strength tests. The results show that two types of warm mixing agents can reduce the mixing and rolling temperatures of the mixture by more than 10°C. The addition of warm mix agents will increase the high temperature stability, water stability, and shear resistance of porous asphalt mixtures. For the improvement effect of high temperature stability, EC120 warm mixing agent is greater than Evotherm M1 warm mixing agent, and for the improvement effect of water stability, Evotherm M1 warm mixing agent is greater than EC120 warm mixing agent. For shear resistance, the improvement effect of both is equivalent, with a penetration strength increase of about 3% to 4%. For low temperature performance, Evotherm M1 warm mixing agent improved the low temperature performance, while EC120 warm mixing agent showed the opposite effect.

Rutting performance of asphalt mixtures containing treated RCA and reinforced by carbon fibers

This study examined the rutting performance of hot asphalt mixtures containing treated RCA and reinforced by carbon fibers. The methodology involved substituting RCA instead of coarse virgin aggregates in the several percentages (20, 40, 60, 80, and 100%) that were treated by being submerged for 24 hours in an acetic acid solution with a concentration of 0.1M. Carbon fibers were added in several percentages of 0.15, 0.25, and 0.35% by the entire weight of the mix to produce cylindrical specimens (4×2.5 inches) for evaluating the Marshall and volumetric properties, and rectangular slabs (30×40×5 cm) for evaluating rutting resistance. The study finds, that incorporating RCA and carbon fibers did not substantially affect the volumetric characteristics of asphalt mixtures, but Marshall's stability increased. The combination containing 60% RCA and 0.35% carbon fibers showed the greatest increase in Marshall stability, which was 35.81% over the control mixture. The addition of RCA led to a reduction in the rutting performance, whereas the addition of carbon fibers increased it, as seen by a decrease in rutting depth. The combination incorporating 40% RCA and 0.35% carbon fibers exhibited a minimum rutting depth of 40.64% lower than the control mixture. The combination incorporating 20% RCA and 0.35% carbon fibers exhibited the maximum level of dynamic stability, which was 1.64 times greater than the control mixture.

Microstructure Analysis and Permanent Deformation of Porous Asphalt incorporating Steel Fiber

Porous asphalt composition is frequently used for the surface extraction layer of pavements because to its open structure and high air void percentage, which lessens disturbance and offers protection during precipitation. Porous asphalt composition has a high air void percentage. This would make it possible for water to be stored horizontally inside the pavement layer as well as moved about within that layer. It is possible that this may lessen the impacts of splash and spray, hence improving drivers’ sight during rainstorms. On the other hand, because to the large percentage of air voids contained inside it, the porous asphalt would be prone to rutting, cracking, and peeling. The goal of this research is to explore the microstructure of porous asphalt that has been mixed with steel fibers in proportions ranging from 0 percent to 0.3 percent. The second objective was to analyze the long-term deformation of porous asphalt that had either 0 or 0.3 percent steel fiber content. In this study, a porous asphalt composition was developed with the help of Marshall mix design. Using sieve analysis, the whole mixture of coarse, fine, filler, bituminous binder, and a range of aggregate sizes was separated into its component parts. Pictures taken using a scanning electron microscope (SEM), an energy dispersive x-ray (EDX), an x-ray diffractometer (XRD), and a fourier transform infrared spectrometer (FTIR) are being used in this inquiry (FTIR). The findings point to the possibility that the performance of porous asphalt mixture might be greatly improved by the addition of steel fiber. Additionally, one may make the case that steel fiber has a longer lifespan than the several other forms of fiber that are used in porous asphalt pavement.

Fracture characteristics of asphalt mixtures containing asphalt millings with geosynthetic fragments

The increasing cost of asphalt and environmental concerns have created a greater interest in exploring the possibility of incorporating higher percentages of reclaimed asphalt pavement (RAP) materials in asphalt mixtures. However, increasing the RAP content can adversely affect some of the properties of asphalt mixtures, including their cracking resistance potential. Consequently, finding a solution that accommodates incorporating higher RAP contents into the asphalt mixture is crucial. Moreover, geosynthetics has gained significant popularity as an anti-reflective cracking system in asphalt pavements, which may lead to the possibility of milling asphalt layers with geosynthetic interlayers. Thus, research studies need to be conducted to understand the characteristics and behaviour of RAP obtained from asphalt layers with geosynthetic interlayers (referred herein as GRAP). The objective of this study is to investigate the cracking characteristics of asphalt mixtures containing different percentages (0, 15, and 30%) of RAP and GRAP material using cross-shear tests. Results indicated that the addition of GRAP into the asphalt mixture by about 30% significantly improves the performance of asphalt mixtures against crack initiation and propagation compared to those asphalt mixtures containing only RAP. Overall, it can be inferred that the presence of geosynthetic fragments could increase the possibility of incorporating higher percentage of RAP in asphalt mixtures.

Correlation between Deformation and Volumetric Characteristics in the Aging Condition of Hot Mix Asphalt

The surface layer of pavement structures tends to experience a decrease in performance as its service life approaches. Generally, this decrease in performance is caused by aggregate degradation and aging of the asphalt binder, which can be caused by traffic loads or weather exposure. The mechanical performance of asphalt mixtures is due to the effects of aggregate degradation, which was simulated by reducing the coarse aggregate fraction and adding medium and fine aggregate fractions. The asphalt aging process simulates changes in binder characteristics by adding RAP binder to Pen 60/70 asphalt. Hot mix asphalt (HMA) with new material (SA-1) as a control for degradation simulation (SA-2, SA-3 and SA-4). Marshall test results show that aggregate degradation significantly causes a decrease in voids in the mixture (VIM) and voids in mineral aggregate (VMA), as well as an increase in voids filled with asphalt (VFA). WTM test results show that HMA degradation causes an increase in rutting depth, which increases the deformation rate and decreases dynamic stability. The correlation results between WTM and Marshall tests show a negative exponential relationship between VIM and VMA with deformation and a positive exponential relationship between VFA and asphalt mixture deformation.

Experimental Study on the Influence of the Superpave and Marshall Design Methods on the Pavement Performance of Asphalt Mixtures

Experimental Study on the Influence of the Superpave and Marshall Design Methods on the Pavement Performance of Asphalt Mixtures

Evaluating the low-temperature performance of asphalt mixtures based on the contraction and relaxation properties

The thermal cracking of asphalt pavement has been the focus of research in cold regions of the world. The contraction and relaxation properties of asphalt mixtures were crucial for investigating the thermal stress of asphalt pavement based on the thermal cracking mechanism. This paper proposed a novel evaluation index for characterizing the low-temperature performance of asphalt mixtures by considering their contraction and relaxation properties. Firstly, the rank during the evaluation indexes for low-temperature performance was determined by comparative analysis of method. Secondly, the thermal contraction coefficient was used to characterize contraction properties and cumulative stress at per unit strain rate (CSSR) was used to characterize relaxation properties in this paper. According to the cumulation process of thermal stress, a novel index was constructed based on the contraction and relaxation properties. Finally, considering the correlation between the failure temperature and the novel indexes, the prediction model of low-temperature performance consistent with the order of failure temperature was established based on the multiple linear regression method. Through the standardized analysis of the prediction model, the influence of novel indexes for the low-temperature performance of asphalt mixtures under different temperature conditions was clarified. A novel evaluation index provided a theoretical basis for unifying the evaluation indexes of asphalt mixtures.

Assessment of Traditional Asphalt Mixture Performance Using Natural Asphalt from Sulfur Springs

This research utilized natural asphalt (NA) deposits from sulfur springs in western Iraq. Laboratory tests were conducted to evaluate the performance of an asphalt mixture incorporating NA and verify its suitability for local pavement applications. To achieve this, a combination of two types of NA, namely soft SNA and hard HNA, was blended to create a binder known as Type HSNA. The resulting HSNA exhibited a penetration grade that adhered to Iraqi specifications. Various percentages of NA (20%, 40%, 60%, and 80%) were added to petroleum asphalt. The findings revealed enhanced physical properties of HSNA, which also satisfied the requirements outlined in the Iraqi specifications for asphalt cement. Consequently, HSNA can serve as an asphalt binder to produce asphalt mixtures for flexible paving construction. Notably, HSNA mixtures exhibited greater Marshall stability and stiffness index when compared to traditional mixtures. The results from indirect tensile strength (ITS) and tensile strength ratio (TSR) tests indicated that the 80NA mixture displayed the highest ITS values and a TSR of 81.36%, surpassing the TSR of the mixture incorporating petroleum asphalt by 0.57%.

Experimental evaluation of fatigue performance of recycled asphalt mixture using refined separation recycled aggregates

In order to improve the utilization of reclaimed asphalt pavement (RAP) in recycled asphalt mixtures (RAMs), RAP was firstly separated into recycled mortar and coarse refined separation recycled aggregates (CRSRAs) with different particle sizes based on a laboratory refined separation method. Meanwhile, the process parameters for RAP separation were optimized by using the orthogonal test method. The related properties of the aggregates before and after refined separation, including residual bitumen binder content, particle agglomeration, angularity, and sphericity, were characterized. The cumulative distribution of sphericity of CRSRAs was fitted with the Weibull function. Asphalt mixtures with 0, 30%, and 50% RAP content were prepared by the Marshall design method. Moreover, the indirect tensile dynamic modulus and fatigue life of these asphalt mixtures after different water immersion periods were evaluated. The results showed that the CRSRAs had a residual binder content less than 1.0% and fewer pseudo particles after refined separation. Furthermore, a bitumen-rich mortar with a particle size less than 2.36 mm and a bitumen content of 10–14% was obtained. Angularity and Weibull fitting results verified that refined separation could homogenize RAP and obtain CRSRAs with a low variability, which helps to prepare better RAMs with high RAP content. RAMs prepared with CRSRAs exhibit superior fatigue performance compared to the traditional RAMs. Their fatigue life was less sensitive to stress changes and fluctuated little with the increasing water immersion time.

Effect of RAP's preheating temperature on the secondary aging and performance of recycled asphalt mixtures containing high RAP content

Plant-mixed hot recycling technology is widely used. Due to concerns about the road performance of recycled asphalt mixtures with high RAP content, the content of RAP is strictly limited, which has negative impact on ecological and economic benefits. Low preheating temperature of RAP material is an important reason for reduced performance of recycled asphalt mixtures containing high RAP content. At the same time, excessive preheating temperature of RAP materials can cause secondary aging of asphalt in RAP. This study regarded the preheating temperature as a variable. Rheological and spectroscopic tests such as DSR and BBR, and FTIR tests were conducted to investigate the effect of RAP preheating temperature on the secondary aging of RAP. Afterwards, the influence of raising preheating temperature of RAP on the performance of recycled asphalt mixtures was explored synthetically. When the preheating temperature is below 160 ºC, there is no significant secondary aging of aged asphalt in RAP. However, when the preheating temperature increases to 180 ºC, the rheological properties of aged asphalt undergo certain changes. Increasing the preheating temperature of RAP can significantly improve the low-temperature crack resistance and fatigue performance of recycled asphalt mixtures by reason of maximally activating the aged asphalt. Increasing the preheating temperature of RAP does not weaken the high-temperature anti-rutting performance of recycled asphalt mixture. It is recommended to control the preheating temperature of RAP at 160 ºC in the design and production process of hot recycled asphalt mixtures.

The crack-healing performance of asphalt mixture based on acoustic emission system

The self-healing properties of asphalt pavements reduce the need for frequent maintenance and repair of cracks and promote road sustainability. In this study, multiple healing tests were conducted under different healing conditions using the semicircular bending "crack-heal-crack" test. The beneficial effects of the healing temperatures and times were determined. However, below 60 °C, the healing index of asphalt mixture does not exceed 0.4. The peak healing indices of the 70# asphalt mixture in the fourth healing stage were 86% of the initial healing index. This correspond to the SBS# asphalt mixture parameters of 88%. Using the acoustic emission system, changes in the ring count and energy of the specimens before and after the healing were compared. The healing index of the cumulative ring count proposed in this study sufficiently correlates with that of the peak load. According to the three-dimensional time-difference positioning method, at the initial loading stage of the prehealing specimen, cracks first appeared at the top of the specimen in contact with the load, then concentrated near the prefabricated incision at the bottom, and finally expanded upward. When the specimen was loaded once again after healing, cracks mainly developed from the bottom upward.

Physics-guided neural network for predicting asphalt mixture rutting with balanced accuracy, stability and rationality

The prediction of rutting performance of asphalt materials poses a significant challenge due to the intricate relationships between the rutting performance and its influencing factors. Machine learning models have gained popularity to address this challenge by offering sophisticated model structures and algorithms. However, existing models often prioritize model accuracy over stability and rationality. The increasingly complicated model structure may lead to an imbalance between the data and the model, resulting in issues such as overfitting and reduced model applicability and interpretability. In this context, this study proposes a novel modeling framework to predict the rutting performance of asphalt mixture by utilizing autoencoder for feature selection and feedforward neural network for rut depth prediction. Notably, physics information of the selected variables is implemented into the neural network to achieve the appropriate balance of model accuracy, stability, and rationality. The results demonstrate that while maintaining high model accuracy, the implementation of physics information significantly enhances the model’s stability and rationality. This framework holds great potential for accurate and reliable predictions of pavement distress by leveraging the complementary strengths of data-driven machine learning and physics-based domain knowledge.

DEM analysis of the effect of geocell on splitting tensile behavior of asphalt mixture based on multi-phase model

Herein, an investigation was conducted upon the reinforcement of geocell on the splitting tensile process of asphalt mixture using laboratory tests and the discrete element method (DEM). Micromechanical modeling of geocell-reinforced asphalt mixture and virtual splitting tensile test was built using PFC3D based on the vital material features and mechanical properties of different ingredients (e.g., the three-dimensional irregular shapes and elastic properties of coarse aggregates and geocell, the viscoelastic properties of asphalt mastic, and the random distribution of air voids in asphalt mastic). Meanwhile, the parameters of the DE model were determined by splitting tensile test, and the effects of geocell on the splitting tensile process of contact force, displacement and stress were evaluated through the virtual splitting test. The results indicated the efficiency of the built DE model and virtual test in effectively predicting the splitting process of geocell-reinforced asphalt mixture. Besides, geocell acted mainly in the falling stage of the load-displacement curve during the splitting process, where the contact force distribution of each phase component shifted from the lower to the higher range, and the effect between coarse aggregates was the greatest, followed between coarse aggregate and asphalt mastic, with the least within asphalt mastic. Further, the maximum displacement of asphalt mixture in the X and Y directions was reduced by the geocell, significantly constraining the coarse aggregate and mastic in geocell-reinforced layer. In addition, the stress in the splitting center of asphalt mixture was greater than that at the sides, and the stress within the geocell of the reinforced layer was significantly lower compared to the unreinforced layer, especially in the falling stage. Overall, the present results forge a theoretical basis for the tensile performance of geocell-reinforced asphalt mixture from the microscopical perspective.

Exploring the low-temperature performance of MPP-modified asphalt binders and mixtures using wet method

Thermal cracking significantly impacts the structural integrity of flexible pavements, particularly in colder regions like Canada. Limited studies investigated the impact of plastic modification of asphalt binders and mixtures using the wet method on the low-temperature performance of asphalt materials. The plastic material utilized in this project is multilayer plastic packaging (MPP). This study aims to determine whether MPP can be integrated to enhance the performance of the MPP-modified binder and MPP-modified mixtures, especially considering that MPP accounts for just over 40% of total plastic usage, making it the largest end-use market segment. This research evaluates the impact on rheological and mechanical behaviour when introducing MPP additives to conventional hot mix asphalt. This study used the wet method to test MPP-modified asphalt materials at 2%, 4%, and 8% (by weight of the asphalt binder). Test results demonstrate that the MPP modification percentage should ideally not exceed 2% as blends with 4% MPP or higher exhibited lower performance at low temperatures. The use of a softer binder as a base binder would help increase the MPP modification rates, but this hypothesis needs to be validated experimentally.

Cooling efficiency of thermochromic asphalt pavement material and its contribution to field performance enhancement of asphalt mixture

The thermochromic asphalt pavement material (TAPM) has the potential to bilaterally regulate the pavement temperature according to seasonal environment, which is beneficial to heat island effect mitigation and pavement performance enhancement. However, studies on quantifying the cooling efficiency and verifying the field performance of TAPM are still limited. This study aims to more extensively verify the cooling efficiency of TAPM in different climatic regions and to reveal its cooling mechanism in the field. The key thermophysical parameter, solar albedo, of TAPM was back-calculated using an interpolation methodology to match the numerical simulation results with the specimen temperature data monitored experimentally. The cooling efficiency of TAPM in broader climatic regions was demonstrated through the numerical simulation combined with real meteorological conditions. In view of the cooling characteristics of TAPM as well as the temperature dependency attribute of asphalt mixture, various field performance properties of TAPM were characterized. It was found that at a temperature larger than 31 ℃, the solar albedo of TAPM is 0.30, which is six times larger than that of the conventional asphalt pavement material, indicating a strong reflection ability to solar radiation. The average temperature reduction of TAPM compared with the conventional asphalt pavement material in different regions is 6.26 ℃ with a standard deviation of 0.79 ℃, demonstrating the effective, universal and stable cooling effect of TAPM in summer across China. The cooling function of TAPM contributes to the improvement of high-temperature stability, aging resistance and low-temperature cracking performance of asphalt mixture. Therefore, it is necessary to consider the unique cooling function of TAPM for a more objective evaluation of its field performance.

Study of Crumb Rubber as Binder Material in Asphalt

Asphalt is a mixture of aggregates, bitumen, quarry dust, and cement. As an addition in hot mix asphalt mixtures, recycled tire rubber known as "crumb rubber" is regarded as an environmentally friendly building practice. The laboratory hot mix asphalt design tests were conducted according to Marshall method procedure. In this study, three different crumb rubber contents (10%, 15%, and 20% by weight of bitumen), and three different bitumen contents (4%, 5%, and 6%) with a penetration grade 60/70 were investigated. The Marshall stability value and durability properties were taken into account in a comparison study between the standard and modified asphalt concrete mixtures. The strength and performance of asphalt mixtures tended to improve with the addition of crumb rubber. As some of the test results were within the acceptable range, the findings indicated that crumb rubber is advised for use as an addition in asphalt mixtures. Besides, the durability of asphalt mixtures also needed to be concerned.

Improving Effects of Pretreated Graphene on Pavement Performance and Self-Healing Behaviors of Asphalt Mixture

Improving Effects of Pretreated Graphene on Pavement Performance and Self-Healing Behaviors of Asphalt Mixture

Red mud application as filler in asphalt mixtures production

Red mud is the solid waste from bauxite processing during aluminium production. Its inadequate disposal causes social, economic and environmental prejudices. The industrial solid waste insertion evaluation in the production chain is beneficial and necessary. This work aims to evaluate the mechanical performance of asphalt mixtures produced with red mud as filling material. Asphalt mixtures with 5% and 7% red mud were produced, and permanent deformation and moisture-induced damage tests were carried out. A mixture without red mud addition (control) was produced for comparison. The results showed that the mixtures with red mud presented permanent deformation resistance greater than the control one, with more than 40% reduction in rutting deformation. The moisture damage did not significantly affect the mixtures tested. The red mud application as a filler in asphalt mixtures is viable and can be an alternative to reduce the damage such a waste can cause to the environment.